Compressor for a system for air-conditioning the passenger compartment of a motor vehicle

ABSTRACT

A compressor for a system for air-conditioning the passenger compartment of a motor vehicle comprises a casing enclosing a system for compressing a refrigerant fluid, an electric motor for driving the compression system and electronic means for control of the electric motor. A low-pressure intake chamber ( 24 ) for the refrigerant fluid is integrated into the casing ( 6 ) and is separated from the high-pressure chamber by a separating partition ( 26 ). The electronic means for control of the electric motor ( 12 ), which are placed in the intake chamber ( 24 ), are cooled by the refrigerant fluid. A separate chamber ( 34 ) for connection of the motor ( 12 ), defined in the casing ( 6 ), communicates with the high-pressure chamber ( 15 ) via a passage ( 36 ). The chambers ( 24 ) and ( 34 ) are closed off by a cover plate ( 20 ) equipped with all the connecting terminals of the compressor.

FIELD OF THE INVENTION

The invention relates to the cooling of the electrical and/or electroniccontrol and monitoring circuits of an air-conditioning system.

BACKGROUND OF THE INVENTION

It relates more particularly to a compressor, especially for a systemfor air-conditioning the passenger compartment of a motor vehicle,comprising a casing defining a high-pressure chamber enclosing a systemfor compressing a refrigerant fluid which circulates in theair-conditioning system, this compression system taking in therefrigerant fluid at low pressure and delivering it at high pressureinto the high-pressure chamber, an electric motor for driving thecompression system and electronic means for control and monitoring ofthe operation of the electric motor.

The compressors used to compress a refrigerant fluid in a system forair-conditioning the passenger compartment of an electrified motorvehicle are controlled by power electronics circuits. The speed ofrotation of the compressor is controlled by an inverter which gives riseto thermal losses during its operation. This is why it is necessary tocool these electronic circuits in order to ensure their operation and toextend their lifetime.

A compressor of the hermetically sealed type is already known (U.S. Pat.No. 6,041,609 DANFOSS) in which the inverter governing the rotationalspeed of the compressor is housed in a box fixed to the outside of thecasing of the compressor, and is cooled by contact and heat exchangewith the intake tube before the refrigerant fluid coming from theevaporator enters the compressor.

A compressor of this type exhibits several drawbacks. It is ofsubstantial size because of the presence, on the outside of thecompressor, of a box in which the electronic components are housed. Itis relatively complex to manufacture and to assemble because it isnecessary to provide a modification to the intake line so that itprovides the necessary and sufficient surface area for contact and heatexchange.

SUMMARY OF THE INVENTION

The subject of the present invention is precisely a compressor of thetype defined in the introduction, which remedies these drawbacks.

This compressor includes a low-pressure intake chamber for therefrigerant fluid integrated in the casing, which is separated from thehigh-pressure chamber by a separating partition, the electronic meansfor control and monitoring of the operation of the electric motor, whichare placed in the intake chamber, being cooled by the refrigerant fluid.

By virtue of these characteristics, a compressor featuring greatcompactness is produced. This compressor can easily be mounted into thevehicle, because there is a single component to be fixed, and a singlearea for connecting the electrical and electronic circuits. The soundlevel of the pulsation of the gas on the intake line of the compressor,as well as the mechanical noises given off by the compression pump andits valve are reduced by the presence of a buffer volume consisting ofthe intake chamber.

The cost of manufacture of this compressor is reduced by the integrationof the electronic circuits for control of the motor of the compressor ina single casing.

Finally, the losses by Joule effect in the phase wires linking theinverter to the motor are reduced to practically nil as a result of theshort length of these connections.

The compressor preferably includes a separate chamber for electricalconnection of the motor, defined in the casing, this separate chambercommunicating with the high-pressure chamber via a passage.

The intake chamber and the separate chamber for electrical connection ofthe motor are advantageously presented as cavities which are opentowards the outside of the casing and are closed off by a cover platewhich is common to the two chambers.

In one preferred embodiment, the cover plate is a terminal plateequipped with all the connecting terminals necessary for the operationof the compressor. The input and output terminals for the power supplyto the electric motor and outlet terminals for motor information (forexample on the temperature of the motor) are situated in a part of theterminal plate which closes off the separate chamber for connection ofthe electric motor, and the other connecting terminals are situated in apart of the terminal plate which closes off the intake chamber.

Advantageously, the outlet terminals from the intake chamber and theinput terminals of the motor in the separate chamber are fixed,permanent and insulated as from delivery of the terminal plate before itis mounted onto the casing of the compressor.

According to another characteristic of the invention, the electronicmeans for control and monitoring of the operation of the compressor arearranged on a power module including a metal cooling sole plate.

According to another advantageous characteristic of the invention, theelectronic means for control and monitoring of the operation of thecompressor are connected to the power module, and these electronic meansand the power module, with the exception of the cooling sole plate, arecoated in an overmoulding of plastic.

This plastic must be compatible with the refrigerant fluid and thelubricating oil of the compressor. It is preferably chosen from thefamily of elastomer polyester thermoplastics. It is preferred to use anelastomer polyester plastic known by the commercial trademark HY-TREL G3548 from the Dupont Company of Nemours.

In one preferred embodiment, the casing is produced as a first partcontaining the gas-compression system, the intake chamber and theseparate electrical-connection chamber, and a second part containing theelectric motor, these two parts being assembled to one another along ajunction plane.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention will emergefurther on reading the description which follows of an embodimentexample given by way of illustration, by reference to the attachedfigures. In these figures:

FIG. 1 is a top view, with cutaway, of a compressor in accordance withthe present invention;

FIG. 2 is a view in section along the line II—II of the compressorrepresented in FIG. 1;

FIG. 3 is a partial view in elevation of the compressor represented inFIG. 1; and

FIG. 4 is a view in section along the line IV—IV of FIG. 2 of a part ofthe casing of the compressor of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 represents a top view of a compressor 2 in accordance with thepresent invention. Such a compressor is intended to form part of asystem for air-conditioning the passenger compartment of a motor vehiclewhich, conventionally, comprises a closed loop for circulation of arefrigerant fluid. The refrigerant fluid, in the gaseous phase,originating from the evaporator (not represented) is taken in at lowpressure into the compressor 2 and delivered at high pressure into acondenser (not represented), from which it emerges in liquid phase.After pressure release, the fluid returns to the evaporator in which ittakes up heat from the surrounding medium, and the cycle repeats.

In the embodiment example represented, the compressor 2 comprises acasing 4 consisting of a first part 6 and of a second part 8. The casing4 is preferably produced from moulded aluminium. Each of the parts 6 and8 includes a flange 9 by which the two parts are assembled to oneanother along a junction plane, for example by means of screws (notrepresented).

The system for compressing the refrigerant fluid 10 is located in thepart 6. A compressor of the type with spirals, also called “scrollcompressor”, will preferably be used. It is also possible to use acompressor of the rotating-piston type. The compression system 10comprises a low-pressure intake chamber into which the gas originatingfrom the evaporator is admitted. It delivers this gas at high pressureinto a high-pressure chamber 15 defined within the casing 4. Theelectric motor 12 driving the compression system 10 is located in thesecond part 8. The rotational speed of this motor can be governed byvarying the frequency of the current and of the voltage which supply it.

The gas originating from the evaporator penetrates into the compressor 2via an inlet orifice 14 so as to be allowed into an intake chamber whichwill be described in more detail later. From the intake chamber, the gasis allowed directly into the compression system 10, then delivered intothe high-pressure chamber 15 which it traverses while cooling theelectric motor 12. The gas leaves the high-pressure chamber 15 throughan outlet orifice 16 as shown diagrammatically by the arrow 17. It isthen led to the condenser (not represented).

The presence of a terminal plate 20 will also be noticed in FIG. 1, thisplate 18 being equipped with all connecting terminals necessary for theoperation of the compressor, as well as the presence of electrolyticcapacitors 18 and of power relays 22, situated close to the terminalplate 20.

As can be seen in FIG. 2, the intake chamber 24 is presented as a cavitywhich is open towards the outside of the part 6 of the casing. It isseparated from the high-pressure chamber 15 by a separating partition26. A communicating orifice 28 is provided in the partition 26. Thisorifice allows the gas to enter into the compression system 10. The gasoriginating from the evaporator penetrates through the intake orifice14, as shown diagrammatically by the arrow 30, passes through thelow-pressure intake chamber 24, then emerges through the communicatingorifice 28 as shown diagrammatically by the arrow 32.

A second chamber 34, smaller than the chamber 24, and itself also beingpresented as a cavity which is open towards the outside of the part 6 ofthe casing, is formed in order to allow the electrical connection of themotor. A passage 36 passing through the casing 4 puts the chamber 34 indirect communication with the motor situated in the high-pressurechamber 15. This passage runs along the side of the part 6 of the casing4 of the motor 12 so as to open out behind the compression system in thepart 8 of this casing.

The chambers 24 and 34 are closed by a common plate which at the sametime constitutes the terminal plate 20. A sealing gasket 40 is providedin order to ensure leaktightness between the intake chambers 24 and 34in order to ensure the leaktightness of each of these chambers with theoutside.

The terminal plate 20 has been represented in front view in FIG. 3. Itincludes six lugs 44 allowing it to be fixed by screws 46 onto the firstpart 6 of the casing 4 of the compressor, thus compressing the sealinggasket 40. The terminal plate groups together all the connectingterminals necessary for the operation of the compressor. At its upperpart are found three input terminals 48 for the three-phase lines whichset out to supply the motor 12, as well as two terminals 50 for outputof information from the motor (for example: the temperature of thismotor). The three connecting terminals 48, as well as the two connectingterminals 50, are situated facing the small, separate chamber 34 and thecommunication passage 36 perforated in the wall 26 lets through theelectrical cables which link these terminals to the motor.

At the lower part of the terminal plate 20 are found the outletterminals 52 for the power-supply phases of the electric motor 12, twoterminals 54 for return of information, a multi-pin terminal 56 for thefunctions of communication with the module for temperature regulation ofthe passenger compartment, the outputs of various protection devicesmanaged by the microcontroller, the control of the relays serving tocharge the input capacitors. Finally, two positive and negative DCpower-supply terminals 58 are found. All these connecting terminals aresituated facing the intake chamber 24.

The output terminals 50 and 52 from the intake chamber 24 and the inputterminals 48 and 54 of the motor in the separate chamber 34 are fixed,permanent and insulated as from delivery of the terminal plate 20 beforeit is mounted onto the casing 4 of the compressor.

For reasons of reliability, permanent insulated connecting bars will beprovided, linking the three motor phases 48 and 52 on the outside of thechambers 24 and 34 as well as the returns of motor information 50 and54.

In FIG. 4 has been represented a view in longitudinal section, along thesection line IV—IV of FIG. 2, of the first part 6 of the casing 4 of thecompressor. The electronic circuits 60 for monitoring and control of thecompressor are housed in the intake chamber 24.

These circuits 60 are based on a power module 62 featuring a metalcooling sole plate. They comprise electronic power components (MOSFET orIGBT) which are encapsulated in the power module 62. Furthermore, thecontrol electronics are mounted on a printed circuit, which is solderedto the power module.

The electronic circuits 60 and the power module 62, with the exceptionof the cooling sole plate, are coated in an overmoulding of a plasticwhich is compatible with the lubricating oil—generally an oil of the POE(polyol ester) type—of the compressor circulating in the refrigerantfluid and with the refrigerant fluid itself.

This plastic is preferably chosen from the family of elastomer polyesterthermoplastics. It is preferred to use an elastomer polyesterthermoplastic known by the commercial trademark HYTREL G 3548 from theDupont Company of Nemours.

The refrigerant fluid, let into the chamber 24 through the intakeorifice 14 (see FIG. 2), passes vertically through the low-pressurechamber 24, lapping over the metal sole plate of the power module 62before re-emerging through the communication orifice 28.

Thus the cooling of the electronic power circuit is ensured withouthaving recourse to a supplementary air or water circuit. The losses fromthe power module are reduced because it is better cooled. Likewise, itsreliability and its lifetime are augmented by reducing its operatingtemperature. Thus effective cooling of the power electronics of thecompressor is achieved without impairing its compactness, and at areduced manufacturing cost.

What is claimed is:
 1. A compressor for air-conditioning a passengercompartment of a motor vehicle, comprising: a casing (4) defining ahigh-pressure chamber (15) enclosing a system (10) for compressing arefrigerant fluid which circulates in the air-conditioning system, saidsystem (10) taking in the refrigerant fluid at low pressure anddelivering said refrigerant fluid at high pressure into thehigh-pressure chamber (15); an electronic means (60) for controlling andmonitoring operation of an electric motor (12); and an intake chamber(24) containing said refrigerant fluid at low pressure, wherein saidintake chamber is integrated into the casing (4) and is separated fromsaid high-pressure chamber (15) via a separating partition (26), whereinthe electronic means (60) for controlling and monitoring operation ofthe electric motor (12) are disposed within the intake chamber (24) andcooled by the refrigerant fluid, wherein the casing (4) is produced as afirst part (6) and a second part, said first part further comprising thesystem (10) for compressing said refrigerant fluid, said intake chamber(24), and a separate chamber (34), and said second part (8) comprisingthe electric motor (12), wherein said first and said second parts areassembled along a junction plane.
 2. The compressor according to claim1, wherein the separate chamber (34) houses an electrical connection ofthe electric motor (12), and communicates with the high-pressure chamber(15) via a passage (36).
 3. The compressor according to claim 2, whereinthe intake chamber (24) and the separate chamber (34) for electricalconnection of the electric motor (12) are cavities which are opentowards the outside of the casing (4) and are closed off by a singlecover plate (20).
 4. The compressor according to claim 3, wherein thecover plate is a terminal plate (20) equipped with all the connectingterminals necessary for operation of the compressor.
 5. The compressoraccording to claim 4, further comprising input terminals (48) for thepower supply to the electric motor (12) and outlet terminals (50) formotor information, wherein said input terminals are disposed on a firstpart of the terminal plate which closes off the separate chamber (34)for connection of the electric motor, and said outlet terminals aredisposed on a second part of the terminal plate which closes off theintake chamber (24).
 6. The compressor according to claim 5, wherein theoutlet terminals (50, 52) from the intake chamber (24) and the inputterminals (48, 54) of the motor in the separate chamber (34) arepermanently fixed and insulated to the terminal plate (20) before saidterminal plate is mounted onto the casing (4) of the compressor.
 7. Thecompressor according to claim 5, wherein the electronic means (60) forcontrol and monitoring operation of the electric motor (12) are arrangedon a power module (62) including a metal cooling sole plate.
 8. Thecompressor according to claim 7, wherein the electronic means (60) forcontrol and monitoring operation of the electric motor are connected tothe power module (62), wherein the electronic means (60) and the powermodule (62) are coated in an overmoulding of plastic.
 9. The compressoraccording to claim 8, wherein the plastic is compatible with therefrigerant fluid and a lubricating oil of the compressor, said plasticis chosen from the family of elastomer polyester thermoplastics.